细沟侵蚀动态过程模拟室内试验和模型验证研究

Simulation study on the dynamic rill erosion processes: model validation with laboratory experiments

进行了一系列室内试验,以验证模拟细沟演变动态过程的数学模型。该模型模拟了细沟水流的动态过程、水力学特性参数的空间变化、细沟中土壤的剥离、运输及沉积过程;模拟了细沟在侵蚀过程中的形态演变,其中包括沟宽、沟深、局部坡度在空间上的差异及其随时间的变化;模拟了细沟侵蚀/泥沙沉积后局部细沟形态的变化对细沟水流反馈效应。试验土壤为砂壤土,采用的坡度为:3%,5%,7%;3个流量:7.6,11.4,15.2L/min。在同一试验条件不同工况下对模型进行了验证,同时对细沟中沿程水流速度和细沟末端的侵蚀产沙量进行了模拟值和试验实测值的对比。结果表明,模型预测值和实测细沟形态演变值具有很好的一致性,模型中提出的侵蚀、沟床形态变化和水力学特性参数间的互反馈环效应可以反映细沟侵蚀的动态演变过程和发展趋势。

A series of laboratory experiments were conducted to verify the simulation model for the dynamic process of rill erosion and evolution. The experiments focused on the validation of the dynamic processes of rill flow, the spatial variation of hydraulic parameters, the soil detachment, transport and deposition; the verification of temporal and spatial evolution of rill morphology, including rill width, flow depth, as well as the local slope gradients; and the validation of feedback effect of local rill morphology change as affected by erosion and deposition on rill flow. The soil material used was a sandy loam. Three slopes: 3%, 5% and 7% and 3 flow rates: 7.6, 11.4 and 15.2 L/min were used in the experiments. Numerical simulations were made on the same conditions as the experiments for different cases for the model verification. Simulated flow velocity values along the rills, sediment concentrations at the rill end were compared with those from the experiments. The results showed that the model prediction was consistent with the measured patterns of morphological changes as the rill evolved, which suggests that the model itself and the feedback loops in the model between erosion, bed morphological changes, and hydraulics were adequate to describe the trend and characteristics of rill erosion dynamics.